Composite wood is known and has been used, for example, as a substitute for wood in areas where wood can deteriorate quickly due to environmental conditions.
Composite wood products typically comprise mixtures of fibers such as waste wood fiber and plastic material preferably recycled plastic material. Such polymer-fiber composites are also known as synthetic wood, composite lumber, wood-polymer lumber and similar such names.
Such composite lumber and its methods of manufacture described, for example, in U.S. Pat. No. 6,344,268 to Stucky et al, issued Feb. 5, 2002; U.S. Pat. No. 5,759,680 to Brooks et al, issued Jun. 2, 1998 and U.S. Pat. No. 5,088,910 to Goforth et al, issued Feb. 18, 1992.
Such composite lumber is commercially available. One such product is manufactured under the trade mark TREX, by Trex Company, LLC of Winchester, Va. and consists of a polyethylene-wood fiber blend which is extruded into board dimensions for decking applications. Such polyethylene-wood composite boards in 5/4 inch thickness have sufficient rigidity to be used as decking planks. Another similar composite wood product containing reclaimed plastic and wood fiber is sold under the trade mark CHOICEDEK by Weyerhaeuser Company of Tacoma, Wash. A similar product is sold under the trade mark WEATHERBEST by ABT Deck Inc. of Portland, Oreg. comprising wood fiber and encapsulated high density polyethylene. A further similar product is sold under the trade mark SMARTDECK by Eagle Brook Products Inc. of Chicago, Ill. and comprising a composite of oak fiber and plastic resins.
Such composite lumber products have a disadvantage referred to as “flagging” created by the use of screws and other fasteners to secure the composite lumber products as, for example, to underlying wooden joists in a decking application. The composite woods are of a plastic nature in the sense that they are, to some extent, plastically deformable. When a typical wood screw is driven into the composite lumber, the wood screw displaces the plastic material to the side with the result that the plastic material becomes displaced from under the head of the screw and urged outwardly therefrom so as to deform the upper surface of the composite material upwardly radially outside of the screw head forming a raised annular ring about the screw head. This raised annular ring presents a disturbing appearance.
It is sometimes possible to reduce the production of the raised annular ring as by drilling a hole through the composite wood product before inserting the wood screw, however, this involves an additional step and, therefore, increases the time and expense.